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SQL Introduction

Mon, 03/09/2009 - 21:59 | hdanzl

Welcome to NexusDB SQL Reference

By choosing NexusDB as your RDBMS, you have acquired access to a modern, state of the art database technology, exposed through standard client data access technologies like Microsoft ODBC and ADO.NET, and Borland VCL and DBExpress.

NexusDB SQL is an interface to the NexusDB core-engine, an advanced and highly efficient relational database management server. This manual provides the information needed to take advantage of the built-in SQL language in NexusDB V3.

Featuring SQL:2003

NexusDB V3 implements a large subset of the international standard ISO/IEC 9075 - SQL:2003, including most of the Core SQL functionality as well as many of the additional features defined in the standard. In addition, NexusDB augments SQL:2003 with extensions to expose vendor-specific functionality.

While NexusDB does not claim official conformance to Core SQL, the grammar conforms closely to the syntax and processing rules defined in SQL:2003. Any difference between NexusDB SQL and SQL:2003 is documented in the Conformance summary at the bottom of each topic page.

The advantage of using standard SQL

While SQL has been the dominant database language for more than three decades, and also being standardized since 1986, the major RDBMS vendors have implemented proprietary grammar and SQL dialects to meet demands in the market not covered by the standard at the time. The result has been that SQL statements tuned to execute efficiently on a particular RDBMS, will often fail when ported to a different RDBMS.

The recent SQL standards, starting with SQL-92, and particularly the SQL:1999 major revision and the latest SQL:2003 minor revision, implement all commercially accepted functionality found in the proprietary implementations, and probably more than a single vendor will ever offer.

It is expected that major RDBMS vendors are currently working on adopting their implementations to the recent standards. By exposing SQL grammar that conforms to SQL:2003 now, NexusDB V3 users have the advantage of being able to write standard SQL statements that can target a variety of RDBMS in a foreseeable future.